tpm: Unify the send callback behaviour

The send() callback should never return length as it does not in every
driver except tpm_crb in the success case. The reason is that the main
transmit functionality only cares about whether the transmit was
successful or not and ignores the count completely.

Suggested-by: Stefan Berger <stefanb@linux.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Tested-by: Alexander Steffen <Alexander.Steffen@infineon.com>
diff --git a/drivers/char/tpm/tpm_i2c_atmel.c b/drivers/char/tpm/tpm_i2c_atmel.c
index 95ce2e9..32a8e27 100644
--- a/drivers/char/tpm/tpm_i2c_atmel.c
+++ b/drivers/char/tpm/tpm_i2c_atmel.c
@@ -65,7 +65,11 @@ static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	dev_dbg(&chip->dev,
 		"%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__,
 		(int)min_t(size_t, 64, len), buf, len, status);
-	return status;
+
+	if (status < 0)
+		return status;
+
+	return 0;
 }
 
 static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count)